In this article we’ll give a brief overview of 4D BIM and Digital Twins (DTs) and explain why the combination can be a powerful addition to every construction project and for long-term facilities management. The general misconception is that DTs can only be useful during operational phases of a project but the truth is that the same concepts can already be applied during construction which then sets the scene for comprehensive holistic operational twin later on.

And if you’re still daunted by the prospect of digital twins, we’ll also offer some advice to help you get started.

What is 4D BIM?

According to the Centre for Digital Built Britain (CDBB), Building Information Modelling (BIM) is the “use of a shared digital representation of a built asset to facilitate design, construction and operation processes to form a reliable basis for decisions”.

Most people are familiar with 3D BIM, where a 3D information model is at the heart of the project and information is shared amongst project participants via a Common Data Environment (CDE).

In recent years, however, the concept of BIM has expanded into different BIM dimensions, with 4D, 5D and even 6D BIM adding time, cost and whole lifecycle management to the mix.

According to the NBS4D BIM adds an extra dimension in the form of time-related scheduling data. 4D BIM effectively takes the data that would typically be contained within a Gantt chart, which maps the sequence of events to complete a project.

By overlaying the time element onto a BIM model, project planners can create an accurate project programme, which with the added visualisation and graphical representation afforded by the BIM model, shows much more clearly how the project will develop.

By mapping the critical path of a project over the model in this way, it is easier to spot problems that could occur—for example, access to particular plant or machinery at different stages of construction—and the project plan can be altered accordingly. By enabling such detailed planning earlier on, this added information can help to improve project safety, while also saving time and costs.

4D risks GIF

What is a digital twin?

More than a virtual digital counterpart, a digital twin is connected to its physical world through data feeds. Digital twins rise from the foundations of BIM, and 3D models developed for construction can form the backbone of an interactive Digital Twin, albeit their use is not compulsory.

A digital twin can be as simple as a spreadsheet with live data feeds via Application Programming Interfaces (APIs), a simple 2D or 3D model of a local component, through to a fully integrated and highly accurate visualisation of an entire collection of assets, with each element dynamically linked to engineering, construction, and operational data as and when needed.

But the transformative potential of digital twins lies in the ability to connect them together to provide deeper insights across a wider context. A virtual replica of a project could provide a ‘single version of the truth’, where all design-build-operate data can be accessed and viewed online on-demand.

Combining 4D BIM and digital twin

Many BIM projects are already exploiting 4D BIM, which adds the element of scheduling and planning over time to 3D models, making it possible to create virtual construction sequences of a project. This helps improve planning and communication across a wide array of stakeholders.

But the ability to run a digital twin of an asset, brought to life by data feeds, offers additional benefits, both short and long-term, across the entire asset lifecycle.

Digital twins can test construction sequencing and logistics scenarios, verify the as-built situation or run ‘what if’ simulations using live data from building sensors to optimise performance and sustainability.

It is important to realise that even upon project delivery, the assets still change over time as units and even whole systems are replaced, partition walls repositioned, extensions added and so on.

HS2 goes 4D with training

Tools to track project progress

Throughout a construction project, there are a number of technologies that can accurately monitor progress and keep an up-to-date record of as-built information through frequent surveys, photogrammetry, LiDAR etc.

Various tools can connect to 4D models to automatically track progress, for example, feeds from site cameras or drones can highlight where work is delayed, ahead of schedule, or detracts from the original design. QR code scanners can track the delivery of components and parts and upload the data into the 4D model.

Robots are currently being trialled that ‘walk’ the site and record detailed 3D as-built information at night, when construction workers are at home, to create a daily record of progress.

Delivering an accurate, real-time record of the project

If all this real-time project data is pushed regularly to a platform like 3D Repo, it can provide an accessible record of the entire project. This not only improves visibility and cost management if the data is structured correctly, but it can also form the basis of a full digital twin for use in long-term asset operation and maintenance, allowing facilities management teams to move away from traditional Computer Aided FM systems.

Data input into BIM during the design and construction phases will provide a vital jumping-off point for the development of a digital twin. One common misconception is that twins must be populated with new data, from sensors in buildings or external sources. Instead, the onus should be on collating and exploiting existing data, generated throughout the course of a project, in a more meaningful way.

How can 3D Repo help?

A digital twin can start as a simple spreadsheet of data held in a central location. A few separate digital twins might perform different functions then connect together at the end of the project to create a more holistic view.

The ability to connect different data sources and share real-time information is essential in the development of a digital twin. And the fastest and easiest way to do this is via APIs.

3D Repo’s open API gives users access to a wealth of data stored on its servers, it permits a growing list of integrations including Asite, Procore, Luminova, Dynamo, and most recently Microsoft Power BI.

The Power BI integration exploits 3D Repo’s free-to-download embeddable viewer, where users can pull models from software like Revit, Navis, IFC, Civil 3D, or Bentley DGN into interactive dashboards to share with colleagues.

By harnessing the power of existing software to create meaningful 4D digital twins, we can all reap the benefits of reduced construction costs, faster project completion, improved on-site health and safety, better-coordinated facilities management and a safer environment for building occupants in the longer term.

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